1. Field of the Invention
The present invention relates to an annular stator component housed in a pump case as a component of a vacuum pump that exhausts gas taken in by rotor rotation in the pump case.
2. Description of the Related Art
A turbo-molecular pump described in Japanese Patent Application No. 4197819, for example, has conventionally been known as a vacuum pump that exhausts gas taken in by rotor rotation in a pump case of the pump. The turbo-molecular pump of Japanese Patent Application No. 4197819 is configured to take in gas from an inlet port (in the vicinity of a flange 14a) by rotating the rotor (R) and exhausts the gas from an outlet port (15a) (see paragraph 0024 of Japanese Patent Application No. 4197819).
According to the turbo-molecular pump of Japanese Patent Application No. 4197819, an internal casing (142) is provided inside the pump casing (14), the rotor (R) is housed in the internal casing (142), and a gap (T) is formed between the internal casing (142) and the pump casing (14) as a way to absorb in the internal casing (142) the energy of fracture that occurs when the rotor (R) is damaged during its rotation (referred to as “fracture energy,” hereinafter). Such a configuration enables the fracture energy to deform the internal casing (142) and enables absorption of the fracture energy by means of the deformation.
However, in the turbo-molecular pump described in Japanese Patent Application No. 4197819, although the fracture energy from the rotor (R) is converted into the energy for deforming the internal casing (142) to absorb the fracture energy, the gap (T) is not set in view of the elongation of the material configuring the internal casing (142). For this reason, sometimes the fracture energy cannot be absorbed sufficiently in spite of the gap (T). In terms of conserving space, providing the gap (T) without taking the elongation of the material into consideration is one of the factors interfering with the attempt to reduce the size of the turbo-molecular pump.
The foregoing reference numerals in the parentheses are used in Japanese Patent Application No. 4197819.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.